ESR Spin Trapping Study of Sodium and Tetramethylammonium Mercaptoundecahydro- closo -dodecaborates(2-) and Sodium Tetraborate Aqueous Solutions Irradiated by UV Light at Room Temperature

The superoxide anion radicals O 2 -• were identified and determined in aqueous solutions of sodium and tetramethylammonium salts of mercaptoundecahydro- closo -dodecaborate(2-) (mercaptoborate), and sodium tetraborate, irradiated by high pressure mercury discharge lamp at room temperature by the of ESR spin trapping method. The quantity of the generated O 2 -. depends on the initial oxygen concentration in the irradiated solutions. The radical generation can play a crucial role in the application of mercaptoborate in boron neutron capture therapy (BNCT) of brain tumours.